This invention relates to a mattress structure and in particular to an improved method of manufacturing an innerspring unit for a mattress.
The conventional mattress includes an innerspring unit, a top cover assembly and a bottom cover assembly. The innerspring unit includes coil springs arranged in linear rows. Each two adjacent coil springs are attached to one another at top and bottom by spring retainer elements.
The top and bottom cover assemblies are each composed of multiple layers of resilient foam material and an outer layer of fabric.
Generally, the mattress provides a balance between two potentially conflicting qualities. The mattress should be firm enough to provide adequate support and should be soft enough that it will not be uncomfortable. For many years, the goal of firmness dominated the mattress industry but more recently the desire for comfort has gained ground. Firmness and softness are each aspects of resilience or elasticity, i.e. the capability of a strained body to recover its size and shape after deformation.
In the conventional innerspring mattress, firmness is provided by the coil springs of the innerspring unit and softness is provided by the foam layers of the top and bottom cover assemblies. If the foam layers of the top cover assembly of a mattress are relatively thin, relatively little load is absorbed by the top cover assembly and most of the load is absorbed by the innerspring unit. In this case, the mattress will feel firmer rather than softer. The mattress might even be termed hard. If the foam layers of the top cover assembly are thicker (for a given resilience), more load will be absorbed by the top cover assembly and less by the innerspring unit, and the mattress will feel softer. However, it is not desirable that the cover assemblies be too thick because a degree of firmness and support is desirable.
As a user applies increasing weight to a conventional innerspring mattress, the weight is first taken up by the deformation of the foam layers of the top cover assembly, and when the foam layers of the top cover assembly are fully compressed, further increase in weight is taken up by the innerspring unit. The user can feel a sudden transition between the softness of the foam layers and the firmness of the innerspring unit, and this can cause the user to feel that in fact the mattress offers little in the way of comfort.
U.S. Pat. No. 5,048,167 discloses a method for restoring a used mattress in which blocks of resilient foam are inserted between the rows of coil springs of an innerspring unit using a tool that forces deformed or displaced springs to their proper positions. U.S. Pat. No. 5,048,167 teaches that in the event that the space between two rows of coil springs has a total height of five inches and a width of two inches, the foam block also should have a height of five inches and a width of two inches. Thus, if the coil springs are in a relaxed state, so that they are not compressed heightwise, the foam block also is relaxed and is not compressed heightwise.
In accordance with a first aspect of the invention there is provided an improved method of manufacturing an innerspring unit for a mattress, wherein the innerspring unit includes upper and lower spring retainer structures in substantially parallel confronting relationship and spaced apart at a predetermined distance, and a plurality of coil springs positioned between and attached to the spring retainer structures, the coil springs being arranged in a plurality of linear rows that are mutually parallel and are spaced apart perpendicular to the length of the rows, whereby a passage is formed between each two adjacent rows of coil springs, wherein the improvement comprises, for each two adjacent rows of springs, providing a resilient element having a height dimension, wherein the height dimension of the resilient element, in a relaxed state, is greater than said predetermined distance, and inserting the resilient element into the passage between the adjacent rows of springs with the resilient element oriented so that the height dimension of the resilient element is substantially perpendicular to the upper and lower spring retainer structures, whereby the resilient element remains partially compressed heightwise between the spring retainer structures.
In accordance with a second aspect of the invention there is provided a method of manufacturing a mattress, comprising providing an innerspring unit that includes upper and lower spring retainer structures in substantially parallel confronting relationship and spaced apart at a predetermined distance, and a plurality of coil springs positioned between and attached to the spring retainer structures, the coil springs being arranged in a plurality of linear rows that are mutually parallel and are spaced apart perpendicular to the length of the rows, whereby a passage is formed between each two adjacent rows of coil springs, providing a resilient element having a height dimension, wherein the height dimension of the resilient element, in a relaxed state, is greater than said predetermined distance, and inserting the resilient element into the passage between the adjacent rows of springs with the resilient element oriented so that the height dimension of the resilient element is substantially perpendicular to the upper and lower spring retainer structures, whereby the resilient element remains partially compressed heightwise between the spring retainer structures.
In accordance with a third aspect of the invention there is provided an innerspring unit for a mattress, including upper and lower spring retainer structures in substantially parallel confronting relationship and spaced apart at a predetermined distance, a plurality of coil springs positioned between and attached to the spring retainer structures, the coil springs being arranged in a plurality of linear rows that are mutually parallel and are spaced apart perpendicular to the length of the rows, whereby a passage is formed between each two adjacent rows of coil springs, and a plurality of resilient elements each having a height dimension, wherein the height dimension of the resilient element, in a relaxed state, is greater than said predetermined distance, wherein the resilient elements are disposed in the passages respectively and are oriented so that the height dimension is substantially perpendicular to the upper and lower spring retainer structures, whereby the resilient elements are partially compressed heightwise between the spring retainer structures.